Deployment and retrieval of seismic autonomous underwater vehicles

ABSTRACT

Apparatuses, systems, and methods for the deployment of a plurality of autonomous underwater seismic vehicles (AUVs) on or near the seabed based on acoustic communications with an underwater vehicle, such as a remotely operated vehicle. In an embodiment, the underwater vehicle is lowered from a surface vessel along with a subsea station with a plurality of AUVs. The AUVs are configured to acoustically communicate with the underwater vehicle or a second surface vessel for deployment and retrieval operations. The underwater vehicle and/or second surface vessel is configured to instruct the AUVs to leave the subsea station or underwater vehicle and to travel to their intended seabed destination. The underwater vehicle and/or second surface vessel is also configured to selectively instruct the AUVs to leave the seabed and return to a seabed location and/or a subsea station for retrieval.

PRIORITY

This application claims priority to U.S. provisional patent applicationNo. 62/072,263, filed on Oct. 29, 2014, the entire content of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to seismology and more particularly relates tothe deployment and retrieval of seismic autonomous underwater vehiclesby an underwater vehicle or surface vehicle.

2. Description of the Related Art

Marine seismic data acquisition and processing generates a profile(image) of a geophysical structure under the seafloor. Reflectionseismology is a method of geophysical exploration to determine theproperties of the Earth's subsurface, which is especially helpful indetermining an accurate location of oil and gas reservoirs or anytargeted features. Marine reflection seismology is based on using acontrolled source of energy (typically acoustic energy) that sends theenergy through seawater and subsurface geologic formations. Thetransmitted acoustic energy propagates downwardly through the subsurfaceas acoustic waves, also referred to as seismic waves or signals. Bymeasuring the time it takes for the reflections or refractions to comeback to seismic receivers (also known as seismic data recorders ornodes), it is possible to evaluate the depth of features causing suchreflections. These features may be associated with subterraneanhydrocarbon deposits or other geological structures of interest.

In general, either ocean bottom cables (OBC) or ocean bottom nodes (OBN)are placed on the seabed. For OBC systems, a cable is placed on theseabed by a surface vessel and may include a large number of seismicsensors, typically connected every 25 or 50 meters into the cable. Thecable provides support to the sensors, and acts as a transmission mediumfor power to the sensors and data received from the sensors. One suchcommercial system is offered by Sercel under the name SeaRay®. RegardingOBN systems, and as compared to seismic streamers and OBC systems, OBNsystems have nodes that are discrete, autonomous units (no directconnection to other nodes or to the marine vessel) where data is storedand recorded during a seismic survey. One such OBN system is offered bythe Applicant under the name Trilobit®. For OBN systems, seismic datarecorders are placed directly on the ocean bottom by a variety ofmechanisms, including by the use of one or more of Autonomous UnderwaterVehicles (AUVs), Remotely Operated Vehicles (ROVs), by dropping ordiving from a surface or subsurface vessel, or by attaching autonomousnodes to a cable that is deployed behind a marine vessel.

Autonomous ocean bottom nodes are independent seismometers, and in atypical application they are self-contained units comprising a housing,frame, skeleton, or shell that includes various internal components suchas geophone and hydrophone sensors, a data recording unit, a referenceclock for time synchronization, and a power source. The power sourcesare typically battery-powered, and in some instances the batteries arerechargeable. In operation, the nodes remain on the seafloor for anextended period of time. Once the data recorders are retrieved, the datais downloaded and batteries may be replaced or recharged in preparationof the next deployment. Various designs of ocean bottom autonomous nodesare well known in the art. Prior autonomous nodes include sphericalshaped nodes, cylindrical shaped nodes, and disk shaped nodes. Otherprior art systems include a deployment rope/cable with integral nodecasings or housings for receiving autonomous seismic nodes or datarecorders. Some of these devices and related methods are described inmore detail in the following patents, incorporated herein by reference:U.S. Pat. Nos. 6,024,344; 7,310,287; 7,675,821; 7,646,670; 7,883,292;8,427,900; and 8,675,446.

Emerging technologies in marine seismic surveys need a fast and costeffective system for deploying and recovering seismic receivers that areconfigured to operate underwater. Newer technologies use AUVs that havea propulsion system and are programmed to move to desired positions andrecord seismic data. After recording the seismic data, the AUVs areinstructed to return to a vessel or underwater base, such as shown inU.S. Publication No. 2014/0301161 and Publication No. WO2014/147165,incorporated herein by reference. Various systems and methods have beenproposed for deploying, guiding, and collecting the AUVs. However, noneof the existing methods fully address the needs of a seismic survey thatuses deployable ocean bottom AUVs to collect the seismic data. Forexample, if AUVs are to be directly deployed and recovered from asurface vessel (besides having sophisticated equipment to allow suchdeployment and recovery), the AUV must have enough power to travel tothe bottom of the seabed and after seismic data collection, resurfaceback to the vessel. This is very challenging, particularly in deep-watersituations. Communications between each AUV and the surface vessellikewise encounter numerous difficulties.

A need exists for an improved method and system for deploying andretrieving AUVs on the ocean bottom, and in particular one thateliminates the requirement for each AUV to directly communicate with asurface vessel and also allows for faster deployment and recovery of theAUVs from a location other than a surface vessel.

SUMMARY OF THE INVENTION

Apparatuses, systems, and methods for the deployment of a plurality ofautonomous underwater seismic vehicles (AUVs) on or near the seabed byusing a remotely operated vehicle (ROV) or other underwater vehicle.Each AUV may comprise one or more seismic sensors, a propulsion system,and a guidance system, and the underwater vehicle may comprise apropulsion system and a guidance system.

In one embodiment, a system for the deployment of seismic nodes on ornear the seabed comprises a plurality of AUVs, a ROV (or underwatervehicle), and one or more surface vessels configured to communicate withthe ROV and/or AUVs. The ROV may be coupled to AUVs that are loweredwith it from a surface vessel. The system may include a subsea station(such as a cage or basket) that is lowered from a surface vessel tocarry additional AUVs to or near the seabed, or in some embodiments thesubsea station is merely lowered a short distance from the water surfaceand AUVs are deployed from that subsea location. The AUVs are configuredto communicate with and be guided by the ROV instead of and/or inaddition to the surface vessel. The ROV is configured to instruct theAUVs to leave the ROV and/or subsea station and travel to their intendedseabed destination. The ROV is also configured to selectively instructthe AUVs to leave the seabed and return to the ROV and/or subsea stationfor retrieval. In some embodiments, a second surface vessel is used tolaunch the AUVs from the subsea station and/or to guide the AUVs from aposition proximate to the subsea station and to the seabed.

In one embodiment, a method for the deployment of a plurality of seismicnodes on or near the seabed comprises positioning a first plurality ofAUVs near the seabed and deploying the first plurality of AUVs atpredetermined positions on the seabed based on communications with anROV or underwater vehicle. A second plurality of AUVs may also bedeployed with the underwater vehicle, whether from a subsea station(such as a cage or basket) or the vehicle itself. The method may alsoinclude recovering the deployed AUVs after a seismic survey has beencompleted. For retrieval, the AUVs may be physically positioned into aROV skid or subsea station by a robotic arm on the ROV, or the AUVs maytravel to another seabed location, the ROV itself, or one or more cagesor subsea stations based on communications provided by the ROV or aseparate surface vessel.

In one embodiment, an apparatus for the deployment of seismic nodes onor near the seabed comprises a ROV and a skid coupled to the ROV,wherein the skid is configured to carry a plurality of AUVs, and whereinthe ROV comprises a guidance system configured to communicate with eachof the plurality of AUVs, wherein the guidance system comprises anacoustic system with one or more transmitters. The ROV may be configuredto deploy the AUVs individually or simultaneously.

In one embodiment, the disclosed deployment system comprises a pluralityof AUVs, a subsea station coupled to a first surface vessel, and asecond surface vessel configured to communicate with each of theplurality of AUVs. The subsea station is configured to be lowered andraised by a surface vessel while carrying a plurality of AUVs. Thesystem may include an underwater vehicle, such as an ROV. The subseastation and underwater vehicle may include an acoustics system and apropulsion system. Each of the subsea station, underwater vehicle,and/or surface vessels may be configured to communicate with each of theAUVs to launch them from the subsea station and to guide them to asubsea position, such as a predetermined location on the seabed. In oneembodiment, a first communications system may launch the AUVs from thesubsea station and a second communications system may guide the AUVsfrom a position near the subsea station to the seabed. The system isconfigured to deploy the AUVs from a surface vessel to a seabed locationand to recover the AUVs from the seabed location to a surface vessel.

In one embodiment, the disclosed deployment method comprises positioninga first plurality of AUVs in a subsea station on a first surface vessel,lowering the subsea station from the first surface vessel to a firstsubsea location, launching the first plurality of AUVs from the subseastation, and deploying each of the first plurality of AUVs at apredetermined position on the seabed. The method may include using anunderwater vehicle or a second surface vessel for communications to eachof the plurality of AUVs, such as launching them from the subsea stationand/or guiding them to the seabed. The method may include launchingadditional pluralities of AUVs from the surface vessel in one or moresubsea station. The method may further include recovering such AUVs fromthe seabed by communications with an underwater vehicle or a surfacevessel into a subsea recovery station, which may or may not be the samesubsea station used to deploy the AUVs.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and areincluded to further demonstrate certain aspects of the presentinvention. The invention may be better understood by reference to one ormore of these drawings in combination with the detailed description ofspecific embodiments presented herein.

FIG. 1 illustrates one embodiment of a schematic diagram of an AUV.

FIG. 2 illustrates another embodiment of a schematic diagram of an AUV.

FIG. 3 illustrates one embodiment of a schematic diagram of a ROV.

FIG. 4 illustrates one embodiment of a schematic diagram for a ROVguidance system.

FIG. 5 illustrates one embodiment of a ROV assisted deployment systemfor AUVs.

FIG. 6 illustrates one embodiment of a ROV assisted deployment systemfor AUVs.

FIG. 7 illustrates one embodiment of a ROV assisted retrieval system forAUVs.

FIG. 8 illustrates one embodiment of a ROV assisted deployment systemfor AUVs.

FIG. 9 illustrates one embodiment of an underwater vehicle assisteddeployment system for AUVs.

FIG. 10 illustrates one embodiment of a subsea station assisteddeployment system for AUVs.

FIG. 11 illustrates one embodiment of a method to deploy AUVs using aROV.

FIG. 12 illustrates one embodiment of a method to recover AUVs using aROV.

FIG. 13 illustrates one embodiment of a method to deploy and recoverAUVs using a subsea station.

DETAILED DESCRIPTION

Various features and advantageous details are explained more fully withreference to the nonlimiting embodiments that are illustrated in theaccompanying drawings and detailed in the following description.Descriptions of well known starting materials, processing techniques,components, and equipment are omitted so as not to unnecessarily obscurethe invention in detail. It should be understood, however, that thedetailed description and the specific examples, while indicatingembodiments of the invention, are given by way of illustration only, andnot by way of limitation. Various substitutions, modifications,additions, and/or rearrangements within the spirit and/or scope of theunderlying inventive concept will become apparent to those skilled inthe art from this disclosure. The following detailed description doesnot limit the invention.

Reference throughout the specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with an embodiment is included inat least one embodiment of the subject matter disclosed. Thus, theappearance of the phrases “in one embodiment” or “in an embodiment” invarious places throughout the specification is not necessarily referringto the same embodiment. Further, the particular features, structures, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Autonomous Underwater Vehicles

In one or more embodiments, an autonomous underwater vehicle (AUV) isused to record seismic signals on or near the seabed. An AUV in thefollowing description is considered to encompass an autonomousself-propelled underwater seismic node that has one or more sensorscapable of detecting seismic waves in a marine environment. Thefollowing embodiments are discussed, for simplicity, with regard to theterminology and structure of an AUV with seismic sensors for recordingseismic waves. In general, the structure and operation of a seismic AUVis well known to those of ordinary skill For example, Applicant's U.S.Pat. No. 9,090,319, incorporated herein by reference, discloses one typeof autonomous underwater vehicle for marine seismic surveys.

FIG. 1 illustrates one embodiment of AUV 100 having a body 102 in whichpropulsion system 103 may be located. Propulsion system 103 may includeone or more propellers 104 and motor 106 for activating propeller 104.Other propulsion systems may be used, such as jets, thrusters, pumps,etc. Alternatively, the propulsion system may include adjustable wingsfor controlling a trajectory of the AUV. Motor 106 may be controlled bya processor/controller 108. Processor 108 may also be connected toseismic sensor 110. Seismic sensor 110 may have a shape such that whenthe AUV lands on the seabed, the seismic sensor achieves a good couplingwith the seabed sediment. The seismic sensor may include one or more ofa hydrophone, geophone, accelerometer, etc. For example, if a 4C (fourcomponent) survey is desired, seismic sensor 110 may include threeaccelerometers and a hydrophone, i.e., a total of four sensors.Alternatively, the seismic sensor may include three geophones and ahydrophone. Of course, other sensor combinations are possible, and mayinclude one or more of a hydrophone, geophone, accelerometer,electromagnetic sensor, depth sensor, MEMs, or a combination thereof.Seismic sensor 110 may be located completely or partially inside body102. Memory unit 112 may be connected to processor 108 and/or seismicsensor 110 for storing seismic data recorded by seismic sensor 110.Battery 114 may be used to power all these components. Battery 114 maybe allowed to shift its position along a track 116 to change the AUV'scenter of gravity. This shift may be controlled by processor 108.

The AUV may also include an inertial navigation system (INS) 118configured to guide the AUV to a desired location. An inertialnavigation system may include a module containing accelerometers,gyroscopes, magnetometers, or other motion-sensing devices. The INS mayinitially be provided with the current position and velocity of the AUVfrom another source, for example, a human operator, a GPS satellitereceiver, a deployed ROV, another INS from the vessel, etc., andthereafter, the INS computes its own updated position and velocity byintegrating (and optionally filtrating) information received from itsmotion sensors. One advantage of an INS is that it requires no externalreferences in order to determine its position, orientation or velocityonce it has been initialized. As noted above, alternative systems may beused, as, for example, acoustic positioning. An optional acousticDoppler velocity log (DVL) (not shown) can also be employed as part ofthe AUV, which provides bottom-tracking capabilities for the AUV. Soundwaves bouncing off the seabed can be used to determine the velocityvector of the AUV, and combined with a position fix, compass heading,and data from various sensors on the AUV, the position of the AUV can bedetermined. This assists in the navigation of the AUV and providesconfirmation of its position relative to the seabed.

Besides or instead of INS 118, the AUV may include compass 120 and othersensors 122 as, for example, an altimeter for measuring its altitude, apressure gauge, an interrogator module, etc. The AUV 100 may optionallyinclude an obstacle avoidance system 124 and a communication device 126(e.g., Wi-Fi or other wireless interface, such as a device that uses anacoustic link) or other data transfer device capable of wirelesslytransferring seismic data and/or control status data. One or more ofthese elements may be linked to processor 108. The AUV further includesantenna 128 (which may be flush with or protrude from the AUV's body)and corresponding acoustic system 130 for subsea communications, such ascommunicating with a deployed ROV (or other underwater station), anotherAUV, or a surface vessel or station. For surface communications (e.g.,while the AUV is on a ship), one or more of antenna 128 andcommunication device 126 may be used to transfer data to and from theAUV. Stabilizing fins and/or wings 132 for guiding the AUV to thedesired position may be used with propulsion system 103 for steering theAUV. However, in one embodiment, the AUV has no fins or wings. The AUVmay include buoyancy system 134 for controlling the AUV's depth andkeeping the AUV steady after landing.

Acoustic system 130 may be an Ultra-Short Baseline (USBL) system, alsosometimes known as Super Short Base Line (SSBL). This system uses amethod of underwater acoustic positioning. A complete USBL systemincludes a transceiver or acoustic positioning system mounted on a poleunder a vessel or ROV (such as Hi-PAP, commercially available byKongsberg) and a transponder on the AUV. In general, a hydro-acousticpositioning system consists of both a transmitter (transducer) and areceiver (transponder). An acoustic positioning system uses anycombination of communications principles for measurements andcalculations, such as SSBL. In one embodiment, the acoustic positioningsystem transceiver comprises a spherical transducer with hundreds ofindividual transducer elements. A signal (pulse) is sent from thetransducer, and is aimed towards the seabed transponder. This pulseactivates the transponder, which responds to the vessel transducer. Thetransducer detects this return pulse and, with correspondingelectronics, calculates an accurate position of the transponder relativeto the vessel based on the ranges and bearing measured by thetransceiver. In one embodiment, to calculate a subsea position, the USBLsystem measures the horizontal and vertical angles together with therange to the transponder (located in the AUV) to calculate a 3D positionprojection of the AUV relative to the ROV or the vessel. An error in theangle measurement causes the position error to be a function of therange to the transponder, so an USBL system has an accuracy errorincreasing with the range. Alternatively, a Short Base Line (SBL)system, an inverted short baseline (iSBL) system, or an inverted USBL(iUSBL) system may be used, the technology of which is known in the art.For example, in an iUSBL system, the transceiver is mounted on or insidethe AUV while the transponder/responder is mounted on the surface vesselor the ROV and the AUV has knowledge of its individual position ratherthan relying on such position from a surface vessel (as is the case in atypical USBL system). In another embodiment, a long baseline (LBL)acoustic positioning system may be used. In a LBL system, referencebeacons or transponders are mounted on the seabed around a perimeter ofa work site as reference points for navigation. The LBL system may usean USBL system to obtain precise locations of these seabed referencepoints. Thus, in one embodiment, the reference beacon may comprise bothan USBL transponder and a LBL transceiver. The LBL system results invery high positioning accuracy and position stability that isindependent of water depth, and each AUV can have its position furtherdetermined by the LBL system. The acoustic positioning system may alsouse an acoustic protocol that utilizes wideband Direct Sequence SpreadSpectrum (DSSS) signals, which provides for a greater communicationsrange in the water.

With regard to the AUV's internal configuration, FIG. 2 schematicallyshows a possible arrangement for the internal components of an AUV 200.While FIG. 2 illustrates an AUV with a submarine-like shape, other AUVbody shapes are possible and include many cross-sectional variations,including low profile, rectangular, triangular, square, circular,flat-bottomed, etc. In one embodiment, AUV 200 includes CPU 202 a thatis connected to internal navigation system (INS) 204 (or compass oraltitude sensor and acoustic transmitter for receiving acoustic guidancefrom the mother vessel), wireless interface 206, pressure gauge 208, andacoustic transponder 210. CPU 202 a may be located in high-level controlblock 212. The INS is advantageous when the AUV's trajectory has beenchanged, for example, because of an encounter with an unexpected object(e.g., fish, debris, etc.), because the INS is capable of taking the AUVto the desired final position as it encounters currents, wave motion,etc. Also, the INS may have high precision. For example, an INS may beaccurate up to 0.1% of the travelled distance, and a USBL system may beaccurate up to 0.06% of the slant range. Thus, it is expected that for atarget having a depth of 1000 m, the INS and/or the acoustic guidance iscapable of steering the AUV within +/−1 m of the desired targetlocation. The INS may be also configured to receive data from a surfacevessel and/or a deployed ROV to increase its accuracy. An optional CPU202 b, in addition to the CPU 202 a, is part of low-level control module214 configured to control attitude actuators 216 and propulsion system218. High-level control block 212 may communicate via a link withlow-level control module 214. One or more batteries 220 may be locatedin AUV 200. A seismic payload 222 is located inside the AUV forrecording the seismic signals. As another embodiment, an obstacleavoidance system may be included in the AUV, which is generallyconfigured to detect an object in the path of the AUV and divert the AUVfrom its original route to avoid contact with the object. In oneexample, the obstacle avoidance system includes a forward-looking sonar.CPU 202 a and 202 b may be coupled with one or more internal componentsto the AUV and provide any necessary control circuitry and software forassociated components. Those skilled in the art would appreciate thatmore or less modules may be added to or removed from the AUV. Forexample, if a seismic sensor is outside the AUV's body, a skirt may beprovided around or next to the sensor. A water pump may pump water fromthe skirt to create a suction effect, achieving a good coupling betweenthe sensor and the seabed. However, there are embodiments in which nocoupling with the seabed is desired. For those embodiments, no skirt isused.

Remotely Operated Vehicle

In general, the structure and operation of marine ROVs are well known tothose of ordinary skill For example, Publication No. WO2014/090811,incorporated herein by reference, describes a ROV configured to deployand retrieve autonomous seismic nodes to the seabed with a separate AUVconfigured to monitor and exchange data with the seismic nodes.Likewise, U.S. Pat. No. 8,075,226, incorporated herein by reference,describes a ROV configured to physically deploy autonomous seismic nodesfrom a carrier located on the ROV as well as a basket lowered by asurface vessel and to mechanically connect the ROV to the lowered basketto transfer nodes from the basket to the ROV carrier. What is lacking inthe prior art, however, is a ROV or other underwater vehicle that isconfigured to deploy seismic AUVs—which have the ability to travelsubsea on their own—based on communications with the underwater vehiclerather than reliance only on a surface vessel communication. Similarlylacking in the prior art is a comprehensive communications system thatis configured to deploy and recover seismic AUVs based on communicationsfrom a plurality of locations, including a second surface vessel(separate from the deployment vessel) and one or more of the cage orROV.

FIG. 3 illustrates one embodiment of an underwater vehicle structure300, which may be an ROV in one embodiment. ROV 300 may have frame 302to which processor 304 and memory storage device 306 are attached.Plural actuators (e.g., propellers) 308 are coordinated by processor 304for guiding the ROV underwater, and may be placed at various positionson frame 302 as is known in the art. ROV 300 may include robotic arm 310for general mechanical operations underwater, including the physicalmovement of the AUVs during deployment and retrieval operations byhandle 311. One or more cameras 312 may be attached to frame 302 formonitoring the positions of the ROV and its robotic arm while subsea. Anoperator may use cameras 312 for driving the ROV, monitoring thedeployment of nodes, and for maneuvering nodes and other equipment. TheROV may include one or more power interfaces 330 configured to transferpower from the ROV to another device, such as AUVs 360. A data andcontrol interface 332 may be used for transferring seismic data from AUV360 to storage device 306, or for transferring operational instructionsto the AUV. In one embodiment, telemetry system 318 is configured totransfer data between ROV 300 and a surface vessel through tether system370. The ROV may be controlled by an operator from the surface throughtether 370. Other electronic components 320 can be provided on the ROVfor particular tasks and/or operations.

In one embodiment, the ROV may be coupled with skid or storage chamber350. In some embodiments, skid 350 may be integrally connected to frame302. Skid 350 is used and configured to store and/or transfer aplurality of AUVs 360 to and from the ROV. Skid 350 may comprise aplurality of baskets that store the nodes. In one embodiment, skid 350comprises a plurality of levels with slots, trays, or conveyors 352 onwhich a plurality of nodes can be stored and/or moved. The trays orconveyors may extend partially out from the skid and/or ROV while theAUVs are being deployed or retrieved from the ROV. In other embodiments,AUVs may move longitudinally along a path in the skid without a trayextending outside of the ROV. In one embodiment, skid 350 may havedimensions of meters, e.g., 3×3×5 meters, and is configured to beflooded with water. Nodes can be loaded onto skid 350 while the ROV ison the marine vessel and prior to the deployment of ROV, and may includea locking mechanism to secure AUVs while the ROV is being lowered fromthe vessel. In other embodiments, AUVs can be transferred to and fromthe ROV underwater via robotic arm 310, which may be attached to handle311 for moving the nodes to and from the ROV. In one embodiment, skid350 may include one or more transfer receptacles 354 to facilitatetransfer of AUVs with the ROV with or without the use of robotic arm310. For example, transfer receptacles 354 may engage and/or couple to acorresponding receptacle on a cage or basket to transfer AUVs betweenthe ROV and cage, and in some embodiments, transfer receptacles 354 alsoprovide power to the cage. Thus, during deployment, trays loaded withAUVs may be transferred to the skid and empty trays from the ROV may bereturned to the cage; likewise, during retrieval, trays loaded with AUVsmay be transferred from the ROV to the cage. Other AUV conveyance andtransfer mechanisms are possible. In some embodiments, AUVs may beconfigured to launch from the ROV or be recovered to the ROV without useof the robotic arm and while the ROV is in motion and hovering above theseabed.

An accurate position of the underwater vehicle is necessary for accuratepositioning of the AUVs. In one embodiment, ROV 300 comprises navigationsystem 314 and guidance system 316. Navigation system 314 is configuredto know the position of the ROV and is capable of guiding the ROV to adesired location. In one embodiment, navigation system 314 may compriseany one or more of the following navigation systems: INS, DVL, USBL,iSBL, iUSBL, LBL, or any combination thereof. In another embodiment, ROV300 further comprises guidance system 316 for the guiding of and/orcommunicating to a plurality of AUVs and other subsea devices. One ormore acoustic systems 315 may be part of and/or coupled to each ofnavigation system 314 and/or guidance system 316. In one embodiment,guidance system 316 may comprise any one or more of the followingnavigation systems: USBL, iSBL, iUSBL, or any combination thereof. Witha known position of ROV 300, the ROV is able to provide more accuratepositioning coordinates to the AUVs. The ROV is able to providepositioning coordinates in local or absolute grid or navigation ordersto the AUVs based on pre-programmed AUV destination coordinates.Alternatively, AUV destination coordinates or guidance can be receivedfrom one or more surface vessels to navigation system 314 after the ROVhas been deployed and when it is at or near the ocean bottom. Each AUVcan then not only be launched from the ROV to move to its intendeddeployment location, but can also calculate its return path back to theROV. Each AUV may be guided to a specific position based on a variety ofnavigation mechanisms and is configured to communicate with the ROV toreceive guidance as to its position and/or destination. In oneembodiment, the AUV knows its absolute position and can act accordinglybased on its own INS and/or navigation system. In other embodiment, theAUV knows its relative position compared to a target or destinationposition and takes appropriate navigation measures to reduce thedistance between its current and destination positions. In still anotherembodiment, the position of the AUV is known by the ROV and the ROVprovides specific guidance to the AUV (such as heading, distance, speed,attitude, position, etc.) for the AUV to reach its intended destination.In one embodiment, the AUV is configured to receive navigation data fromthe ROV on the ROV's position (such as ROV speed, pitch, roll, heading)and to use such data in connection with its navigation system and toproperly position the AUV in reference to the ROV.

FIG. 4 illustrates one embodiment of a schematic illustration ofnavigation system 400 that may be used by the ROV, which may comprisecontrol system 410 that interfaces with guidance system 420 and acousticsystem 470. In some embodiments, some or all of the components shown inFIG. 4 may be used with any underwater vehicle or subsea cage or basket.While not shown, navigation system 400 may be coupled to any number ofmodules or components on the ROV, such as processor 304. In oneembodiment, navigation system 400 comprises clock 412, navigation device418, and additional electronic components 414. Navigation device 418 mayinclude an inertial navigation system (see, e.g., INS 204), an attitudeand heading reference system (AHRS), or another similar device, such asa Doppler Velocity Log (DVL). Navigation device 418 is used fordetermining an accurate position and orientation of the ROV, includingposition, true heading, attitude, speed and heave of the ROV. In oneembodiment, navigation device 418 is configured to interface with one ormore elements of any acoustic positioning equipment on the ROV and/oracoustic system 470. Thus, in one embodiment, navigation system 400and/or acoustic system 470 may communicate with one or more surfacevessels to obtain and/or verify the position of the ROV.

In one embodiment, navigation system 400 includes guidance system 420for the guiding of and/or communicating to a plurality of AUVs. In otherembodiments, guidance system 420 is separate from and operatesindependently of navigation system 400 and acoustic system 470, but isconfigured to interface with navigation system 400 and/or acousticsystem 470. In one embodiment, guidance system 420 is configured tocommunicate with a plurality of AUVs and to provide guidance todeparting and/or arriving AUVs from the ROV while deployed in the ocean.In one embodiment, acoustic system 470 may be any one or more of USBL,iSBL, iUSBL, or any combination thereof and is used to communicate withand position the ROV from a surface vessel.

In one embodiment, acoustic system 470 may comprise a plurality ofacoustic transmitters 472 a-b, acoustic transceiver 476, and acousticmodem 478. In some embodiments, clock 412 may be used for transmissionsrequiring synching, as is known in the art. Acoustic modem 478 is neededif there is an exchange of information or messages in an acousticsignal/message. Transceiver 476 communicates with an acousticpositioning system of a surface vessel and/or other sub-surface vesselor station (such as an AUV). In one embodiment, acoustic system 470interfaces with guidance system 420 to position the plurality of AUVs.In another embodiment, acoustic system 470 is used to position both theROV and the plurality of AUVs, and management and guidance of the ROVand AUVs is provided by a surface vessel, such as the deployment vesselor a second surface vessel. In this embodiment, the ROV is configuredwith one or more transponders, as well as an acoustic modem and a clock.In other embodiments, acoustic system 470 is configured to communicatewith one or more surface vessels and/or one or more AUVs.

In one embodiment, acoustic system 470 comprises transmitter 472 a atproximately each of the top corners of frame 402 of the ROV andtransmitter 472 b attached to stand 473 in the top middle portion of theROV. The stand 473 provides a different height and elevation to at leastone of the plurality of transmitters. The transmitters 472 can belocated at other positions of the ROV. Having more transmitters isdesirable so that during a seismic survey, each AUV has a “direct view”of at least three transmitters for positioning itself. In oneapplication, at least two of the transmitters are positioned within abase of a pyramid, while at least one of the transmitters is positionedat the top of the pyramid. In this arrangement, each AUV has thecapability to position itself in a horizontal and vertical planerelative to the ocean bottom. In one application, a distance between twotransmitters may be in the order of meters, for example, 2.5 meters, andwith such a configuration, it is expected that an AUV could detect itsposition from 1 km away with good precision (e.g., within 1 m). As thetechnology improves, it is expected that these numbers will become evenbetter. In one embodiment, each transmitter 472 emits pings and has nocapability to receive signals. A transmitter may include a ceramicelement that emits the acoustic signal and corresponding electronicsunit that interacts with control system 410 and also controls theceramic element. In one embodiment, the system of transmitters may forma short base line (SBL) system. In another embodiment, the acousticsystem may form an inverted short baseline (iSBL) system.

In one embodiment, each AUV deployed in the ocean has a differentchannel or code based on spread spectrum domain as to which it receivesand sends communications. For example, an AUV may be configured toreceive low frequencies in the range of 40 kHz, which provides for longdistance communications. Thus, control system 410 and/or guidance system420 is programmed to select appropriate frequency channels for thetransmitters, to adjust the channels if necessary, and to synchronizethe transmitters. In one embodiment, transmitters 472 are configured tosend a plurality of communications over a range of frequencies, eachfrequency corresponding to a separate AUV, which can be selectivelyfiltered by an AUV during reception of the transmission. Guidance system420 is configured to send information from the transmitters to the AUVs.In one embodiment, guidance system 420 is configured to interrogate theAUVs about their position and status, selectively instruct one or moreof them to return to the ROV, etc. Similar embodiments may be used inconnection with deployment from a second surface vessel that ispositioned proximate to the AUVs or a subsea cage or basket.

In one embodiment, the configuration of the guidance system and/oracoustic system on the ROV has a corresponding match on each of theAUVs. For example, in one embodiment, the ROV comprises a transceiverand a plurality of transmitters while each AUV comprises at least onetransponder. Alternatively, the ROV may comprise a plurality oftransponders while each AUV comprises a transceiver. In eitherembodiment, each of the AUVs and ROV may also comprise a clock(particularly if the acoustic positioning system is synchronous) and anacoustic modem.

System and Operation

Generally, a deployment vessel stores a plurality of AUVs and a separateshooting vessel may be used to generate seismic waves. The shootingvessel may tow one or more seismic source arrays, each one includingplural source elements. A source element may be an impulsive element(e.g., a gun) or a vibratory element. In one embodiment, the deploymentvessel also tows and shoots source arrays as it deploys the AUVs. Whenthe AUVs are in recording position (on the seabed), seismic waves aregenerated, which are recorded by the sensors on the AUVs. In oneembodiment, the number of AUVs is in the thousands. In one embodiment,the deployment vessel is configured to hold all of the AUVs at thebeginning of the seismic survey and then to launch them as the surveyadvances.

As discussed above, with the use of an ROV or other underwater vehiclewith the necessary installed systems, in one embodiment the AUVs neednot have to communicate with the deployment vessel; instead, each AUVneeds only to communicate with the deployed ROV. This system is muchmore accurate, fast, and cost effective than current systems to deployseismic AUVs on the seabed. Further, the use of an ROV assisted guidancesystem for AUVs solves many problems with the prior art, as describedabove. In still other embodiments, a second surface vessel may be usedthat is positioned closer to the deployed AUVs than is possible with thedeployment vessel. This second vessel may be used in addition to the ROVor in lieu of the ROV to send communications to the plurality of AUVsand to guide them to and from a seabed location. Still further, thelowered basket or cage itself may include various communication systemsthat are configured to launch the AUVs from the cage and to deploy themto the seabed (with or without communications from the ROV or secondsurface vessel). In these embodiments, one or more communicationssystems are used (separate from the deployment vessel) to facilitatedeployment and retrieval of the AUVs.

FIG. 5 illustrates one system for using an ROV or other underwatervehicle to position a plurality of autonomous seismic nodes on or nearseabed 3. In one embodiment, deployment vessel 510 launches ROV 550 intothe ocean from surface 1. Deployment vessel 510 also launches cage orbasket 520 (which may be any container or structure that is capable ofholding a plurality of AUVs suitable for transfer to the seabed, whichmay or may not include a communications systems and a propulsion system)into the ocean, which may occur before, during, or after the deploymentof ROV 550. In one embodiment, cage 520 includes a frame or housing witha base that is configured to land on the seabed. The cage may include aplurality of levels or slots that are configured to each hold aplurality of AUVs, such as on a conveyor, conveyor belt, carousel, ortray. The cage may also include a connecting mechanism for connecting toa hook or other connecting device extending from a support vessel, aswell as a coupling mechanism for connecting to an ROV for the transferof AUVs to and from the ROV. ROV 550 is configured with skid 530 orother similar AUV storage structure (which may be substantially similarto skid 350) that can hold a first plurality of AUVs 501 a.

In one embodiment, ROV 550 is lowered into the ocean via umbilical cable512 and cage 520 (after being loaded with a plurality of AUVs while onboard vessel 510) is lowered into the ocean by wire 522. In oneembodiment, both the ROV 550 and cage 520 are lowered on or near theseabed with first plurality of AUVs 501 a and second plurality of AUVs501 b, respectively. In some embodiments, cage 520 is lowered only asmall distance beneath surface 1. In other embodiments, plurality ofAUVs 501 b are only lowered to the seabed in cage 520 without AUVs 501 abeing lowered with ROV 550. In one embodiment, ROV 550 knows theapproximate initial deployment location for the AUVs and may find itsdesired position using, for example, an inertial navigation system(INS), which may be part of and/or coupled to guidance system 552 on ROV550. Guidance system 552 may be substantially similar to acoustic system315 and/or 470 of ROV (see FIGS. 3 and 4). ROV is configured to know itsposition based on communications with surface vessel 510 (or othersurface vessels). ROV 550 is configured to communicate with surfacevessel 510 via umbilical cable 512 and/or acoustic positioning system511 located on the vessel. In some embodiments, use of a neutrallybuoyant tether or tether management system to ROV 550 can also beutilized, which is particularly helpful in deep-water applications. Theuse of umbilical 512 connected to the ROV provides a much faster datatransfer than acoustic communications via acoustic positioning system511, and may result in an increased update speed of the data with ROV550.

Once ROV 550 reaches a location proximal to the intended deploymentlocation for AUVs 501 a, a signal is sent from guidance system 552 toactivate AUVs 501 a that are stored in ROV 550. Once activated, one ormore of the AUVs 501 a travel to their destination (which may be on theseabed or proximal to the seabed) to get positioned for recordingseismic waves. In one embodiment, each AUV 501 a has its own channel orcode based on spread spectrum domain such that ROV 550 can selectivelycommunicate with each AUV. In one embodiment, each AUV 501 a may bepreprogrammed or partially programmed prior to launch from the ROV tofind its destination position using an INS of the AUV and thecoordinates of ROV 550 as a reference point. However, in anotherapplication, AUV 501 a finds its desired position using a combination ofacoustic guidance, waypoint navigation and information from variousnavigation sensors such as an inertial measurement unit, echo sounder,pressure gauge, etc., including communications from guidance system 552.Other systems or methods may be used for finding their desiredpositions. After launch from ROV 550, AUV 501 a is configured tocommunicate with guidance system 552 to determine the position of AUV501 a and find its destination in route. The final details, positions,and/or coordinates for finding the desired destination position of AUV501 a may be received, acoustically, from ROV 550. Once AUV 501 a landsat its destination on the seabed, the final destination point can becommunicated to and/or verified by ROV 550. In one embodiment, thelaunching of AUVs 501 a is performed while surface vessel 510 is stillmoving in the general direction of the intended seismic survey pattern,while in other embodiments surface vessel 510 remains substantiallystationary on the surface. In one embodiment, a plurality of AUVs 501 acan be launched from ROV 550 at a particular time, such that all AUVsleave the ROV at or near the same time. In other embodiments, one ormore of the plurality of AUVs 501 a are launched at a particular timebased upon the intended destination location, such that a plurality ofAUVs may remain with the ROV as one or more AUVs are deployed. The useof ROV 550 to guide AUVs 501 a provides a much faster, reliable, andaccurate method to position seismic AUVs on the seabed than currenttechniques.

Once all or substantially all of AUVs 501 a have been launched from ROV550, second plurality of AUVs 501 b that are stored in cage 520 can bedeployed in a similar manner. In another embodiment, a second pluralityof AUVs 501 b can be launched from cage 520 at or near the same timethat a first plurality of AUVs 501 a are launched from ROV 550. In oneembodiment, AUVs 501 b are launched directly from cage 520 based oncommunications with guidance system 552. In another embodiment, ROV 550moves towards the position of cage 520 and retrieves AUVs 501 b andstores them in skid 530 of ROV 550 after the first plurality of AUVs 501a have been deployed. In one embodiment, transfer receptacles 354 on ROV550 (see FIG. 3) engage with cage 520 to transfer AUVs 501 b or trays ofAUVs 501 b to the ROV 550. Robotic arm 310 on ROV 550 may or may not beused to facilitate the transfer of AUVs 501 b and/or the positioning ofAUVs on the seabed. In one embodiment, skid 530 and/or cage 520 maycomprise one or more conveyor belts or lateral moving mechanisms thattransfer the AUVs from cage 520 to ROV 550.

As shown in FIG. 6, once all of second plurality of AUVs 501 b havetransferred from cage 520, cage 520 is raised to surface 1 by surfacevessel 510 to obtain a new set of AUVs. Meanwhile, first plurality ofAUVs 501 a have been deployed to seabed 3 or are in transit to theirdestinations, and second plurality of AUVs 501 b (previously transferredfrom cage 520) remain stored in ROV 550 while awaiting launchinstructions from ROV 550. In one embodiment (not shown), by the timethe second plurality of AUVs 501 b have been deployed from ROV 550, cage520 has been re-lowered to a location proximate the ROV (or a separatelocation to which the ROV may travel to) with a new set of AUVs, whichcan be deployed in a similar manner as described above. This process, oflowering and raising cage 520 with a new plurality of AUVs and the AUVsbeing deployed by ROV 550, can be repeated numerous times until therequired amount of AUVs have been positioned and/or the survey has beencompleted. Because the launching of AUVs is performed while surfacevessel 510 is still moving in the general direction of the intendedseismic survey pattern, a great number of AUVs can be deployed fast andaccurately.

While ROV 550 can be deployed by vessel 510, other vessels (such asshooting vessels or unmanned surface vessels) can also deploy ROV 550before or near the time that cage 520 is lowered. Thus, a first surfacevessel may deploy the ROV and a second surface vessel may deploy thecage and multiple pluralities of AUVs. In other embodiments, multiplecages or ROVs can be used to provide even faster deployment times forthe AUVs. In one embodiment, the AUVs may be configured to alsocommunicate with acoustic positioning system 511 on the deploymentvessel 510 in addition to ROV 550, which may function as a backupcommunications system.

Once the survey is complete, or a particular portion of the survey iscomplete such that a group of AUVs no longer needs to remain on theseabed, a signal is selectively provided to a plurality of AUVs by ROV550 to initiate recovery. The selected AUVs may be chosen from a givenrow or column if that type of arrangement is used. In one embodiment,the recovery is performed in a reverse manner as the launch, asdescribed above. For example, each selected AUV communicates with ROV550 and moves toward ROV 550 using an INS or acoustic communicationssystem on the AUV. In another embodiment, ROV 550, a surface vessel, ora subsea station (such as cage 520) may be configured to send acousticsignals to the returning AUVs to guide them to the desired position. Inone embodiment, the AUVs are guided into skid 530 for recovery. In otherembodiments, robotic arm 310 is used to grab or secure a particular AUVand insert it into skid 530. In still another embodiment, when selectedAUVs are instructed to leave their recording locations, they may beprogrammed to go to a desired rendezvous point where they will becollected by ROV 550 at a later time. In still other embodiments, ROV550 is moved towards each AUV (or selected AUVs in which their power hasbeen depleted) to grab the AUV and insert it into skid 530. Once asignificant amount of AUVs has been recovered in ROV 550, the ROV 550can transfer the AUVs individually or in groups (via trays or conveyors)to cage 520. Once full, cage 520 can be raised to a surface vessel(which may or may not be the same deployment vessel) while ROV 550recovers additional AUVs from the seabed. In still other embodiments,the plurality of AUVs are configured to travel directly to a loweredcage or other subsea station without assistance by the ROV.

In other embodiments, ROV 550 is not configured with a guidance systemand/or does not communicate with the AUVs for positioning or guidance.Rather, each AUV communicates with acoustic positioning system 511 onsurface vessel 510 or a separate surface vessel (see FIGS. 8-10) oranother acoustic positioning system deployed in the ocean (such as anunderwater base station, cage 520, or another AUV, which may beconnected to a surface vessel via a wire). In this embodiment, ROV 550is still configured to hold a plurality of AUVs and transfer AUVs fromcage 520 to skid 530, but all communications between and directions tothe AUVs are performed through a separate communications system.Likewise, for recovery of the AUVs, ROV 550 can grab the AUVs and placethem in skid 530 and/or cage 520 for ultimate recovery to the surfacevessel. While in this embodiment the ROV does not directly provideguidance to the positioning of the AUVs, the use of an ROV fordeployment and/or recovery with a separate cage 520 provides asignificant increase in deployment and recovery speeds as opposed tocurrent techniques. Further, this eliminates the need for powerfulbatteries in the AUVs that are able to be deployed to or near the seabedfrom a surface vessel and travel back to the surface vessel from theseabed. Still further, this eliminates the need for a complicatedretrieval system on the surface vessel to retrieve the AUVs from theocean after the seismic survey has bee completed. Still further, thiseliminates the need for the AUVs to directly communicate with a surfacevessel, which takes more time, power, and is not as accurate ascommunicating with a local ROV or other underwater vehicle or stationthat is more proximate to the AUVs.

FIG. 7 illustrates another embodiment for the recovery of AUVs using anROV. This system is similar to the system described in FIG. 5, bututilizes a station or cage 720 that is used in addition to or asreplacement of skid 530 of ROV 550. Cage 720 is configured to sit onseabed 3 and store a plurality of AUVs 701 b. In this embodiment,guidance of AUVs 701 a is still performed through guidance system 552 ofROV 550, as described above in relation to FIGS. 5 and 6. In thisembodiment, one or more cages 720 can be deposited on the seabed beforeor after the deployment of AUVs 701 a on or near the seabed (such asdescribed in FIGS. 5 and 6). Once the survey is complete, or aparticular portion of the survey is complete such that a group of AUVs701 a no longer needs to remain on the seabed, a signal is provided to aplurality of AUVs 701 a to initiate recovery. The AUVs 701 a are thenguided to cage 720 for temporary storage as stored AUVs 701 b withincage 720. The AUVs can be guided via acoustic positioning system 511,guidance system 552, or even a beacon or array of transmitters (notshown) on cage 720, which may be similar to acoustic system 315 and/or470 of ROV (see FIGS. 3 and 4). In other embodiments, the ROV may alsoplace the AUVs into cage 720, which may be useful if any of the AUVs donot have enough power to return to the cage. When desired, one or moreROVs can retrieve cages 720 and attach them to line 522 for recovery toa surface vessel.

FIG. 8 illustrates another system for using an ROV to assist in theguidance of AUVs on or near the seabed. This system is similar to thesystem described in FIG. 5, but utilizes a second vessel 820 forcommunications with ROV 550. In one embodiment, vessel 820 is anunmanned surface vessel (“USV”), and in some embodiments it may be afloating buoy with a communications system. In one embodiment, ROV 550is connected to surface vessel 510 via umbilical system 512. In otherembodiments, ROV 550 may be connected to USV 820 by umbilical system512. USV 820 may be utilized in addition to or as a replacement ofsurface vessel 510 for communications with ROV 550 and/or the pluralityof AUVs. In one embodiment, USV 820 is equipped with acousticpositioning system 821, which may be similar to the acoustic positioningsystem 511 located on deployment vessel 510. USV 820 is configured tocommunicate with deployment vessel 510 with a variety of communications,preferably wirelessly. Because USV 820 may be positioned closer to ROV550 than the deployment vessel 510, USV 820 may provide faster andbetter communications with ROV 550. Another embodiment uses bothdeployment vessel 510 and USV 820 to communicate with ROV 550 and/or theplurality of AUVs. The use of two transducers or acoustic positioningsystems that communicate with ROV 550 from the different vessels (asopposed to one) increases the electrical and acoustic redundancy of thecommunications based on two independent measurements. The dual systemuses both transducers from the vessels to measure the position of onesingle target transponder (located on the ROV) by separately controllingthe beam forming and phase measurement for each system in parallel. Thisprovides greater accuracy of the AUV positioning and quality control. Amore accurate position of ROV 550 provides better data and accuracy toposition the AUVs at the desired locations. In another embodiment, aplurality of USVs may be used to communicate with ROV 550 to providestill better accuracy regarding the location of ROV 550. In otherembodiments, one or more surface buoys (not shown) may be used inaddition to or as a replacement of USV 820 for communication with ROV550. In still other embodiments, one or more underwater stations or AUVs(not shown) may be used in addition to or as a replacement of USV 820for communication with ROV 550. In one embodiment, ROV 550 may bedeployed or launched by USV 820 instead of deployment vessel 510. Instill another embodiment, AUVs may be configured to communicate withboth USV 820 (or another surface vessel or device) and vessel 510. Instill other embodiments, the AUVs may be configured to communicate with(and be guided and/or instructed by) cage 520 if the cage is equippedwith the necessary communications equipment.

In another embodiment, an AUV is dropped from an ROV (such as from thebottom of the ROV or a skid of the ROV) while the ROV is moving. Thus,the ROV need not actually touch the bottom of the seabed duringdeployment of the AUVs Likewise, the AUVs can be recovered to the movingROV while the ROV is in motion above the seabed. In other embodiments,the AUVs can be recovered to a skid or cage that is located above theseabed and as it is moved laterally along with a surface vessel. Instill other embodiments, a plurality of ROVs and/or a plurality of skidsor cages can be towed by one or more surface vessels to deploy and/orrecover a plurality of AUVs.

FIG. 9 illustrates another embodiment for the recovery of AUVs using anunderwater vehicle, which may or may not be an ROV. Similar to thesystem described in FIG. 8, this system uses second surface vehicle 820to help guide the AUVs during subsea operations. Basket or cage 960 isconfigured to be lowered (and raised) by surface vessel 510 to a subseaposition, which may be on or near seabed 3, in the middle of the ocean,or near the surface of the ocean a relatively short distance fromsurface 1. Cage 960 may be configured with communications system 962 andpropulsion system 964, while in some embodiments cage 960 may not haveany communications system or propulsion system. Cage 960 is configuredto hold a plurality of AUVs 501 in the cage, which may be held in thecage by any number of arrangements, whether by conveyor, conveyor belt,chain, carousel, skid, basket, etc. As in earlier embodiments, any AUVsmay be positioned in the cage while on the back deck of surface vessel510. Communications system 962 may be configured to communicate withother communications systems 511, 821, and 952, as well as thecommunications systems on each of the plurality of AUVs 501. In someembodiments, cage 960 may have one or more transmitters or pingersconfigured to transmit acoustic signals (or pings) that may be detectedby the AUVs for deployment or retrieval operations. Propulsion system964 may include any number of thrusters, propellers, nozzles or similardevices known to those of skill in the art to move a subsea basket orstation from a first subsea position to a second subsea position,including any such propulsion system that may be used on an ROV as isknown in the art.

Underwater vehicle 950 is configured to be lowered by vessel 510 to asubsea position, which may be on or near seabed 3, in the middle of theocean, or near the surface of the ocean a relatively short distance fromsurface 1. While in one embodiment underwater vehicle 950 is an ROV, itneed not be an ROV. For example, underwater vehicle 950 need not have anarm and it may be a cage or AUV configured with communications system952 and propulsion system 954. Underwater vehicle 950 may be coupled tosurface vessel 510 via wire or umbilical cable 912, which in someembodiments may allow data and power to be communicated to underwatervehicle 950 so that it can stay subsea during longer periods of time andhave faster data rates. In some embodiments, communications systems 952is an acoustic guidance system that may be configured to interact withacoustic system 511 of first vessel 510, acoustic system 821 of secondvessel 820, acoustic system 962 of cage 960, and/or the plurality ofAUVs 501. While the underwater vehicle may have or be coupled to a skidor cage to hold a plurality of AUVs, such a holding assembly is notnecessary in this embodiment. The system described in FIG. 9 operatessubstantially similar to the prior embodiments with underwater vehicle950 providing some guidance to the deployment of AUVs 501 from cage 960and/or to the seabed. In the embodiment shown in FIG. 9, however,underwater vehicle 950 does not physically retrieve, grab, or move anyAUVs. Instead, underwater vehicle 950 is used solely as a positioningand/or guidance system for the deployment and/or retrieval of theplurality of AUVs. In some embodiments, underwater vehicle 950 and/orsecond vessel 820 may actively travel closer to one or more deploymentlocations for increased communications accuracy and/or speed to theplurality of AUVs in that general deployment location. This allows theAUVs to be positioned on the seabed with enhanced accuracy. Theconfiguration described in relation to FIG. 9 allows cage 960 to beraised back to surface vessel to obtain a second plurality of AUVs whilethe first plurality of AUVs are being deployed by another vehicle, suchas by second vessel 820 or underwater vehicle 950, and allows increasedcommunications efficiency and accuracy with the AUVs during deploymentto the seabed. In other words, a separate vehicle may be positioned moreproximate to the intended deployment position on the seabed or near theAUVs as they are deploying to the seabed, whether the second vehicle issecond vessel 820 or underwater vehicle 950. Thus, a communicationssystem on each AUV must be configured to interface with a communicationssystem on each or both of surface vessel 820 and/or underwater vehicle950, and in one embodiment such a communications may be one of USBL,iSBL, iUSBL, or any combination thereof. In one embodiment, theplurality of AUVs may be launched from cage 960 based uponcommunications provided to the plurality of AUVs from one of manypotential locations, including first surface vessel 510, second surfacevessel 820, underwater vehicle 950, or cage 960. The plurality of AUVsmay be launched individually, sequentially, or near simultaneously. Inone embodiment, once one or more of the plurality of AUVs leaves cage950 and arrives at a second subsea position, a second station or vesselmay take over the guidance and/or positioning of the AUVs to land at theintended seabed location. In other words, while a first vehicle ordevice (such as cage 960 and/or first vessel 510) may instruct the AUVsto leave the cage, a second vehicle (such as underwater vehicle 950 orsecond vessel 820) may instruct, guide, and/or position the AUVs totheir final seabed destination. In some embodiments, for increasedpositioning accuracy and faster communications, second vessel 820 may bepositioned proximate to a subsea position substantially where the AUVsare to be deployed (such as being located on the water surface at apoint substantially over one or more of the intended deploymentlocations of the AUVs) and/or underwater vehicle 950 may be positionedproximate to the position of the deployed AUVs (which may be near theseabed).

Each of the plurality of AUVs may have a predetermined location onseabed 3 as to which it will land, couple with the seabed, and recordseismic signals during any seismic survey. During any retrievaloperations, a recovery station may be utilized, which is in oneembodiment the same as or substantially similar to cage 960. In oneembodiment, one of the surface vessels or underwater vehicle 950provides a communication to each of the selected AUVs to wake up andreturn to a recovery station and/or cage after the seismic survey hasbeen completed. Such communications may include the subsea location ofthe recovery position and/or cage. In some embodiments, recovery stationand/or cage 960 may include a homing array and/or a plurality oftransmitters or pingers that is configured to emit a plurality ofacoustic signals or pings to which the plurality of AUVs may be guidedto during retrieval operations, which allows for increased accuracyand/or positioning of the AUVs to the cage when in a close proximity tothe cage. Such a system may be similar to the acoustic guidance systemand/or communications system described in relation to FIG. 4 or thesystems disclosed in Publication No. WO 2014/147165 and US PublicationNo. 2014/0301161, each incorporated herein by reference. In someembodiments, multiple cages may be used at the same time, such that agreater number of AUVs may be deployed and/or retrieved at a given time.

FIG. 10 illustrates another embodiment for the recovery of AUVs using anunderwater vehicle. This system is similar to the system described inFIG. 9, but does not use a second subsea vehicle besides cage 960.Similar to the systems described in FIGS. 8 and 9, this system usessecond surface vehicle 820 to help guide the AUVs during one or moresubsea operations. Basket or cage 960 is configured to be lowered (andraised) by surface vessel 510 to a subsea position, which may be on ornear seabed 3, in the middle of the ocean, or near the surface of theocean a relatively short distance from surface 1. In one embodiment,cage 960 is substantially similar to the cage described in relation toFIG. 9, and thus may or may not have communications system 962 andpropulsion system 964. Like the system described in relation to FIG. 9,it may be configured with a homing system or set of transmitters orpingers. In one embodiment, cage 960 is lowered to a first subseaposition with a plurality of AUVs. One or more of the plurality of AUVsmay be launched from cage 960 based on communications from cage 960,first vessel 510, or second vessel 820. In one embodiment, second vessel820 travels to a surface position proximate to the intended deploymentposition of the AUVs. Once the AUVs have left the cage and havetravelled to a first subsea position and/or are in route to a subseaposition, first vessel 510 and/or second vessel 820 may providecommunications to the AUVs to actively guide and/or position them to apredetermined destination on the seabed. The cage may raised and filledwith a new set of AUVs, which may be deployed again in a similar manner.During retrieval operations, the AUVs may be sent a signal to wake-upand/or move to a subsea recovery position, which may be on or near theseabed or proximate to cage 960. Such communications may be provided tothe AUVs by cage 960, first vessel 510, or second vessel 820. In oneembodiment, each AUV has a homing array that guides the AUV towards oneor more pings or signals emitting from cage 960. In some embodiments,multiple cages may be used for faster deployment and/or recovery of theAUVs.

FIG. 11 illustrates one embodiment of a method 1100 for assisting withthe deployment of a plurality of seismic AUVs with an ROV or otherunderwater vehicle. In an embodiment, the method includes providing atleast one ROV on or near the seabed, as shown in block 1102. In oneembodiment, the ROV may be lowered by a first surface vessel and may ormay not comprise a first plurality of AUVs (such as being located withina skid of the ROV). The ROV has a guidance system for communicating witha plurality of AUVs. The method further includes providing at least onesurface vessel to communicate with the at least one ROV, as shown inblock 1104. The surface vessel can be a deployment vessel, a shootingvessel, an unmanned surface vessel (USV), or other surface vessels orstations. The vessel may have an acoustic positioning system that isconfigured to communicate with the ROV, but in some embodiments may onlybe connected to the ROV via a wire and/or umbilical system. In oneembodiment, the ROV is configured to determine its subsea position basedupon acoustic communications with the surface vessel. In someembodiments, the acoustic positioning system of the surface vessel canalso communicate with a plurality of AUVs. The method further includesproviding at least one subsea station configured to hold a plurality ofAUVs, as shown in block 1106. In one embodiment, the subsea station is abasket or cage filled with a second plurality of AUVs that is deployedfrom the same vessel that provides or deploys the ROV. In otherembodiments, a separate vessel deploys the subsea station. The subseastation may be deployed on the seabed (which may be preferred forstability reasons) or merely hang on a connecting wire from the surfacevessel a certain distance above the seabed or beneath the surface. Instill other embodiments, the subsea station may be connected to anunderwater vehicle, such as a skid. In one embodiment, the ROV isdeployed first on or near the seabed, while in another embodiment thesubsea station is deployed first on or near the seabed. The methodfurther includes positioning a plurality of AUVs on the seabed based oncommunications with the ROV, as shown in block 1108. The plurality ofAUVs may be those located on the subsea station and/or those located onthe ROV itself. The first plurality of AUVs may be deployed first or thesecond plurality of AUVs may be deployed first. In some embodiments, thefirst plurality of AUVs (within the skid) are deployed first and then aportion of the second plurality of AUVs are transferred to the ROV andthen subsequently deployed when the ROV is in a position proximate tothe intended destination location. In other embodiments, the AUVs arelaunched directly from the subsea station based on communicationsprovided by the ROV. In one embodiment, a guidance system on the ROVinteracts with an acoustic communications system or INS on each AUV toprovide the AUV directions and coordinates as to the intended deploymentlocation. The AUVs may be deployed along a predetermined pattern, e.g.,a regular grid based on predetermined coordinates. In one embodiment, aparticular AUV is selectively instructed to wake up and travel to aseabed destination based on the AUV's propulsion system and guidancesystem receiving commands from the ROV's guidance system. An AUV may bedeployed one at a time until it arrives at its seabed location, or aplurality of AUVs may be deployed simultaneously or near the same time.In some situations, the ROV may travel to the general area proximate tothe seabed destination with a group of AUVs and then deploy the relevantAUVs. The ROV may verify the positions of the AUVs and confirm that theyare located at the correct locations in the predetermined grid. In oneembodiment, the method further comprises providing a third plurality ofAUVs proximate to the ROV, as shown in block 1110. The third pluralityof AUVs may be lowered by the same subsea station (such as the samebasket or cage) that delivered the second plurality of AUVs. In otherembodiments, a separate vessel or station may deliver the thirdplurality of AUVs proximate to a location proximate to the ROV or to theintended AUV seabed destination. The method further comprisespositioning the third plurality of AUVs on or near the seabed based oncommunications with the ROV, as shown in block 1112. This positioningstep may, but not necessarily, be performed in the same way as describedin step 1108. Once the AUVs are in place and operational, the AUVs areready to acquire and record seismic data. During the recordal of seismicdata, the ROV may confirm that the AUVs are active and recording data,along with the status of other components (e.g., power unit capacity,data storage capacity, etc.). If a particular AUV needs to be replacedand/or is no longer working, the ROV may retrieve the problematic AUVand replace it with another AUV that is located in the ROV skid.

FIG. 12 illustrates one embodiment of a method 1200 for assisting withthe recovery of a plurality of seismic AUVs with an ROV or otherunderwater vehicle. In an embodiment, the method includes providing atleast one ROV on or near the seabed, as shown in block 1202. The ROV mayor may not comprise a skid that is configured to hold a plurality ofAUVs. The ROV has a guidance system for guiding and/or communicatingwith a plurality of AUVs. The method further includes providing at leastone subsea recovery station configured to hold a plurality of AUVs, asshown in block 1204. In one embodiment, the subsea station is a cage orbasket that is deployed from a surface vessel, and may or may not be thesame station used to deploy the AUVs to the seabed. In otherembodiments, a separate vessel provides the subsea recovery station. Inother embodiments, a plurality of subsea stations has been positioned onthe seabed in proximity to one or more groups of AUVs. In still anotherembodiment, the subsea station is a skid or other holding device that ispart of or coupled to an underwater vehicle, such as the ROV. In someembodiments, the subsea station is not positioned near the seabed but ismerely positioned in the body of water at some distance beneath thevessel and/or water surface. The method further includes communicatingwith a plurality of AUVs on or near the seabed, as shown in block 1206.These AUVs may or may not have been previously positioned by an ROV. Inone embodiment, the AUVs are located on the seabed and need to berecovered to the surface for data recovery after their recording ofseismic waves. In one embodiment, the ROV communicates with each of (ora portion of) the plurality of AUVs, in which a particular AUV isselectively instructed to wake up and travel to a subsea recoverydestination based on the AUV's propulsion system and guidance systemreceiving commands from the ROV's guidance system. The method furtherincludes recovering and/or positioning a plurality of AUVs into at leastone subsea recovery station based on assistance by the ROV, as shown inblock 1208. In one embodiment, the assistance is based on acousticcommunications between the ROV and the plurality of AUVs. In thisembodiment, a guidance system on the ROV interacts with an acousticcommunications system or INS on each AUV to provide the AUV directionsand coordinates as to the intended subsea recovery location, which maybe a single spot on the seabed, within the ROV, or in the subseastation. In other instances, the ROV assistance is the grabbing orsecuring of the plurality of AUVs by the ROV, such as by a robotic arm,and the placement of the AUVs in the intended subsea station. Thesecommunicating and positioning steps can be repeated multiple times untilall of the AUVs are recovered in one or more subsea stations. In oneembodiment, the plurality of AUVs and/or the plurality of subseastations are recovered to a surface vessel.

FIG. 13 illustrates another embodiment of a method 1300 for assistingwith the deployment of a plurality of seismic AUVs. In one embodiment, asubsea station with a plurality of AUVs is launched from a first surfacevessel to a subsea position, as shown in block 1302. The subsea stationmay be a cage or basket or other similar structure configured to holdand deploy a plurality of AUVs subsea, while in other embodiments it maybe coupled to an underwater vehicle. The subsea position may be on ornear the bottom of the ocean, in the middle of the ocean, or near thesurface of the ocean. The subsea station may or may not have an acousticguidance system and/or a propulsion system. One or more of the pluralityof AUVs are then launched from the subsea station based uponcommunications provided to the one or more plurality of AUVs from one ofvarious locations or devices, including a first surface vessel, a secondsurface vessel, an underwater vehicle (such as an ROV), or the subseastation itself, as shown in block 1304. The plurality of AUVs may belaunched individually, sequentially, or near simultaneously. In oneembodiment, the AUVs leave the subsea station and travel to a secondsubsea position to await further commands. The second subsea locationmay be a subsea position near the station, near a separate vessel orvehicle, or on or near a seabed position. A separate vehicle may bepositioned to a position proximate to the one or more launched AUVsand/or to a position where the AUVs are to be deployed on the seabed, asshown in block 1306. In some embodiments, a second surface vehicle orvessel (such as vessel 820) may be positioned proximate to a subseaposition where the AUVs are to be deployed. Likewise, an underwatervehicle (such as a ROV) may be positioned proximate to the position ofthe deployed AUVs. Once the AUVs have been launched from the subseastation, the one or more AUVs are guided to a predetermined seabedlocation for the recording of seismic data, as shown in block 1308. Thetrajectory of the AUV may be adjusted in real time based on receivedcommunications. In one embodiment, once one or more of the plurality ofAUVs leaves the subsea station and arrives at a second subsea position,a second vehicle, station, or vessel may take over and/or assist withthe guidance and/or positioning of the AUVs to land at a seabedlocation. In other words, while a first vehicle or device (such as thebasket or first surface vessel) may instruct the

AUVs to leave the subsea station, a second vehicle or device (such as anunderwater vehicle or second vessel) may instruct, guide, and/orposition the AUVs to their final seabed destination. In someembodiments, the position of the AUV may be determined based uponcommunications with multiple systems, such as by one or more surfacevehicles, an underwater vehicle, and/or the subsea station. In someembodiments a single AUV is launched from the subsea station anddeployed to a seabed location, while in other embodiments a plurality ofAUVs are launched from the subsea station and deployed to a plurality ofseabed locations. While the first plurality of AUVs is being deployed tothe seabed (and after the AUVs have left the subsea station), the subseastation is raised back to the first surface vessel for transferring asecond plurality of AUVs to the subsea station. Similar to the priorsteps, the second plurality of AUVs may be launched from the subseastation (based on instructions by a first communications system) andonce freely travelling in water may be guided and/or positioned toanother subsea position (such as a predetermined location on the seabed)by a second communications system.

After the seismic survey is completed, which may be days or months afterbeing positioned on the seabed, the plurality of AUVs must be retrievedto a surface vessel. In some embodiments, the method 1300 includesvarious retrieval operations for the plurality of deployed AUVs. Forexample, method 1300 may include recovering one or more of the deployedAUVs at a subsea position, as shown in block 1310. In one embodiment,the plurality of AUVs are instructed to travel to a first subseaposition from each of their deployed seabed locations, which may be onor near the seabed or proximate to a subsea recovery station. Such aposition may be near the seabed or near the surface of the body ofwater. In one embodiment, a separate vehicle or station (such as firstor second surface vessel, underwater vehicle, or the recovery basket orstation) communicates the coordinates of the subsea position to theplurality of AUVs, along with any necessary wake up commands and otherinstructions. In some embodiments, the AUVs may travel to a positionnear the intended recovery position (or underwater vehicle, cage, orbasket) or the recovery station may travel to a position proximate tothe plurality of AUVs. Method 1300 may further include retrieving theone or more AUVs into a subsea recovery station, as shown in block 1312.The subsea recovery station may or may not be the same subsea stationused to deploy the AUVs, and it may include a cage, basket, or similarholding structure, and may or may not be coupled to an underwatervehicle. For example, once the AUVs are in a position proximate to therecovery station, the AUVs are instructed to return to the recoverystation. In one embodiment, one of the surface vehicles, an underwatervehicle, and/or recovery station itself (such as a basket) communicatesthe coordinates of the recovery position and/or recovery station to theplurality of AUVs. In some embodiments, the AUVs are guided to therecovery station by a homing array that detects one or more pings oracoustic signals emitting from the recovery station. Once the AUVs areloaded onto the subsea recovery station, it may be raised back to arecovery vessel (which may or may not be the same vessel as thedeployment vessel), the AUVs transferred from the recovery station tothe vessel, and an empty recovery station returned to a subsea positionfor loading of additional AUVs. Steps 1310 and 1312 may be repeateduntil the necessary amount of AUVs has been retrieved from the seabed.In some embodiments, multiple recovery stations, such as multiplebaskets, may be used simultaneously. In one embodiment, the AUVs aredeployed from a subsea station from a position substantially near theocean surface while the AUVs are retrieved into a subsea station on orsubstantially near the seabed.

All of the methods disclosed and claimed herein can be made and executedwithout undue experimentation in light of the present disclosure. Whilethe apparatus and methods of this invention have been described in termsof preferred embodiments, it will be apparent to those of skill in theart that variations may be applied to the methods and in the steps or inthe sequence of steps of the method described herein without departingfrom the concept, spirit and scope of the invention. In addition,modifications may be made to the disclosed apparatus and components maybe eliminated or substituted for the components described herein wherethe same or similar results would be achieved. All such similarsubstitutes and modifications apparent to those skilled in the art aredeemed to be within the spirit, scope, and concept of the invention.

Many other variations in the configurations of a node and the wirelesssystems on the node and/or vessel are within the scope of the invention.For example, the AUV may be of any configuration, and may be designed tocouple to the seabed or merely near the seabed. In one embodiment, afirst vessel may act as a deployment vessel, a second vessel may act asa retrieval vessel, and a third vessel may act as the seismicsource/shooting vessel. As another example, the ROV may not comprise arobotic arm and may simply act as a deployment and/or retrieval guide bythe use of its communications system and/or acoustic guidance system. Inother embodiments, a subsea station, cage, or other underwater vehiclemay be used to provide commands and/or acoustic communications with theplurality of AUVs. In still other embodiments, the AUVs may be deployedfrom a cage and retrieved to that cage without the use of a ROV. It isemphasized that the foregoing embodiments are only examples of the verymany different structural and material configurations that are possiblewithin the scope of the present invention.

Although the invention(s) is/are described herein with reference tospecific embodiments, various modifications and changes can be madewithout departing from the scope of the present invention(s), aspresently set forth in the claims below. Accordingly, the specificationand figures are to be regarded in an illustrative rather than arestrictive sense, and all such modifications are intended to beincluded within the scope of the present invention(s). Any benefits,advantages, or solutions to problems that are described herein withregard to specific embodiments are not intended to be construed as acritical, required, or essential feature or element of any or all theclaims.

Unless stated otherwise, terms such as “first” and “second” are used toarbitrarily distinguish between the elements such terms describe. Thus,these terms are not necessarily intended to indicate temporal or otherprioritization of such elements. The terms “coupled” or “operablycoupled” are defined as connected, although not necessarily directly,and not necessarily mechanically. The terms “a” and “an” are defined asone or more unless stated otherwise. The terms “comprise” (and any formof comprise, such as “comprises” and “comprising”), “have” (and any formof have, such as “has” and “having”), “include” (and any form ofinclude, such as “includes” and “including”) and “contain” (and any formof contain, such as “contains” and “containing”) are open-ended linkingverbs. As a result, a system, device, or apparatus that “comprises,”“has,” “includes” or “contains” one or more elements possesses those oneor more elements but is not limited to possessing only those one or moreelements. Similarly, a method or process that “comprises,” “has,”“includes” or “contains” one or more operations possesses those one ormore operations but is not limited to possessing only those one or moreoperations.

What is claimed is:
 1. A system for the deployment of seismic nodes onor near the seabed, comprising a plurality of autonomous underwatervehicles (AUVs), wherein each AUV comprises one or more seismic sensors,a propulsion system, and a guidance system; a remotely operated vehicle(ROV), wherein the ROV comprises a guidance system configured tocommunicate with each of the plurality of AUVs and to guide each of theplurality of AUVs from a first subsea position to a second subseaposition; and a surface vessel configured to communicate with the ROV.2. The system of claim 1, further comprising a skid coupled to the ROV,wherein the skid is configured to carry a first plurality of the AUVs.3. The system of claim 2, further comprising a subsea station coupled tothe surface vessel, wherein the subsea station is configured to carry asecond plurality of the AUVs, wherein the subsea station is configuredto be lowered from the surface vessel to a subsea position.
 4. Thesystem of claim 3, wherein the ROV is configured to couple with thesubsea station to transfer a plurality of AUVs between the subseastation and the ROV.
 5. The system of claim 1, wherein the ROV isconfigured to instruct each of the plurality of AUVs to launch from asubsea station and travel to a seabed location.
 6. The system of claim1, wherein each of the plurality of AUVs is configured to determine itssubsea position based on acoustic communications with the ROV.
 7. Thesystem of claim 1, wherein the plurality of AUVs may be deployed from afirst surface vessel while the ROV is coupled to a second surfacevessel.
 8. The system of claim 1, wherein each of the plurality of AUVshas a different channel or code based on spread spectrum domain as towhich it receives and sends communications.
 9. A method for thedeployment of a plurality of seismic nodes on or near the seabed,comprising positioning an underwater vehicle at a location proximate tothe seabed, wherein the underwater vehicle comprises an acousticguidance system and a propulsion system, positioning a first pluralityof autonomous underwater vehicles (AUVs) in a subsea station, whereineach AUV comprises one or more seismic sensors, a propulsion system, anda guidance system; positioning the subsea station at a subsea position;and deploying the first plurality of AUVs at predetermined positions onthe seabed based on communications provided by the underwater vehicle.10. The method of claim 9, wherein the underwater vehicle is a remotelyoperated vehicle (ROV).
 11. The method of claim 9, further comprisingtransferring the first plurality of AUVs from the subsea station to theunderwater vehicle.
 12. The method of claim 9, further comprisinglaunching the first plurality of AUVs from the subsea station based oncommunications provided by the underwater vehicle.
 13. The method ofclaim 9, further comprising recovering one or more of the firstplurality of AUVs from the seabed to a subsea position based oncommunications with the underwater vehicle.
 14. The method of claim 9,further comprising recovering one or more of the first plurality of AUVsfrom the seabed into a subsea station by a robotic arm on the underwatervehicle.
 15. The method of claim 9, further comprising positioning asecond plurality of autonomous underwater vehicles (AUVs) near theseabed; and deploying the second plurality of AUVs at predeterminedpositions on the seabed based on communications with the underwatervehicle.
 16. The method of claim 15, wherein the positioning of thesecond plurality of AUVs comprises lowering a skid from a surfacevessel, wherein the skid is coupled to the underwater vehicle, whereinthe skid is configured to hold the second plurality of AUVs.
 17. Asystem for the deployment of seismic nodes on or near the seabed,comprising a plurality of autonomous underwater vehicles (AUVs), whereineach AUV comprises one or more seismic sensors, a propulsion system, anda guidance system; a subsea station coupled to a first surface vessel,wherein the subsea station is configured to carry a first plurality ofthe AUVs and be lowered from the first surface vessel to a subseaposition, wherein the subsea station comprises a communications systemconfigured to communicate with each of the plurality of AUVs; and asecond surface vessel configured to communicate with each of theplurality of AUVs.
 18. The system of claim 17, wherein the subseastation is configured to position the plurality of AUVs from a firstsubsea position to a second subsea position.
 19. The system of claim 17,wherein the second surface vessel is configured to position theplurality of AUVs from a first subsea position to a second subseaposition.
 20. The system of claim 17, wherein the second surface vesselis configured to position each of the plurality of AUVs from a positionproximate to the subsea station to a predetermined position on theseabed.
 21. The system of claim 17, further comprising a first guidancesystem and a second guidance system, wherein the first guidance systemis configured to launch one or more of the plurality of AUVs from thesubsea station and the second guidance system is configured to guide oneor more of the plurality of AUVs to one or more seabed locations. 22.The system of claim 17, wherein the second surface vessel is configuredto instruct the plurality of AUVs to return to a subsea position forrecovery.
 23. The system of claim 17, wherein the subsea stationcomprises a plurality of pingers that is configured to emit signals tothe plurality of AUVs, wherein each of the AUVs comprises a homing arraythat is configured to detect the transmitted signals during recovery tothe subsea station.
 24. A method for the deployment of a plurality ofseismic nodes on or near the seabed, comprising positioning a firstplurality of autonomous underwater vehicles (AUVs) in a subsea stationon a first surface vessel, wherein each AUV comprises one or moreseismic sensors, a propulsion system, and a guidance system; loweringthe subsea station from the first surface vessel to a first subsealocation; launching the first plurality of AUVs from the subsea station;and deploying each of the first plurality of AUVs at a predeterminedposition on the seabed.
 25. The method of claim 24, further comprisingguiding the first plurality of AUVs to one or more seabed locationsbased on communications provided by a second surface vessel.
 26. Themethod of claim 24, further comprising guiding the first plurality ofAUVs to one or more seabed locations based on communications provided bythe subsea station.
 27. The method of claim 24, further comprisinglaunching the first plurality of AUVs from the subsea station based oncommunications provided by the subsea station.
 28. The method of claim24, further comprising launching the first plurality of AUVs from thesubsea station based on communications provided by a second surfacevessel.
 29. The method of claim 24, further comprising launching thefirst plurality of AUVs from the subsea station based on communicationsprovided by a first communications system and guiding the firstplurality of AUVs to one or more seabed locations based oncommunications provided by a second communications system.
 30. Themethod of claim 24, further comprising raising the subsea station to thefirst surface vessel; positioning a second plurality of AUVs in thesubsea station; lowering the subsea station to a subsea position;launching the second plurality of AUVs from the subsea station; anddeploying each of the second plurality of AUVs at a predeterminedposition on the seabed.
 31. The method of claim 24, further comprisingrecovering the first plurality of AUVs to a subsea recovery stationbased on signals provided by the recovery station.